Burkina Faso international Traore signed his first professional contract at Chelsea in 2013, at the age of 18, but was not registered until January 2014.

Mediapart claimed Fifa found evidence that Chelsea had misled them over the dates, while Traore was found to have made 25 appearances for the Blues at various levels – under-16, under-18 and first team – despite not being registered by the FA.

Chelsea admitted they paid his mother £155,000, as well as a further £13,000 to the club she chaired – AJE Bobo-Dioulasso – in April 2011 to allow them first refusal over his signature.

That deal, it is alleged, was for four-and-a-half years, despite the limit for under-18s being three years.

In addition, it is also claimed Chelsea paid for Traore to attend the £20,000-a-year Whitgift School in Surrey.

Real Madrid and Atletico Madrid both received bans for breaching rules over the signing of minors in early 2016, while fellow Spanish club Barcelona were given a 14-month ban after breaking rules for signing international under-18s in 2014.

However, a Barcelona appeal saw their punishment pushed back a year, allowing the club to sign Luis Suarez, Ivan Rakitic, Jeremy Mathieu, Claudio Bravo and Marc-Andre ter Stegen.

What are Fifa’s rules?

Fifa bans the transfer of under-18s to different countries unless they meet strict criteria. It brought in the rules to help protect children from exploitation and trafficking.

Under-18s can only be transferred abroad if:

The player’s parents move to the country in which the new club is located for non-footballing reasons.

Both clubs are in the European Union or European Economic Area and the player is aged between 16 and 18. Even then, the buying club must meet more criteria relating to education, training, living conditions and support.